Community gardens are viewed as a potentially useful environmental change strategy to promote active and healthy lifestyles but the scientific evidence base for gardens is limited. As a step towards understanding whether gardens are a viable health promotion strategy for local communities, we set out to examine the social processes that might explain the connection between gardens, garden participation and health. We analyzed data from semi-structured interviews with community gardeners in Denver. The analysis examined social processes described by community gardeners and how those social processes were cultivated by or supportive of activities in community gardens. After presenting results describing these social processes and the activities supporting them, we discuss the potential for the place-based social processes found in community gardens to support collective efficacy, a powerful mechanism for enhancing the role of gardens in promoting health.